To determine the characteristics of certain objects, particularly characteristics that require instruments to observe, it is often necessary to obtain images of the object and then to perform measurements on the image. For example, microscopic structures are often viewed and measured using electron microscope images. Similarly, astronomical images from telescopes are used to facilitate measurement of large, but distant astronomical objects.
“Microfabrication” is the fabrication of extremely small structures. Microfabrication processes are used, for example, to produce structures in integrated circuits, to build magnetic heads for reading and writing to magnetic media, and to fabricate miniature mechanical or electromechanical devices. During microfabrication, it is necessary to measure critical dimensions to ensure that the process is operating properly and that the parts being produced meet the product specification.
For example, recording heads for disk drives are fabricated on ceramic wafers by a number of methods including but not limited to cutting the desired shape with a focused ion beam, photolithography and broad-beam ion etching. These devices are three dimensional and need to be managed or controlled in all three dimensions. One method of verifying that the recording heads are of the proper dimension is to cleave the wafer, that is, break it along a line running through the recording head, and measure the width of the recording head along the exposed cross-section. This method is time consuming and costly. Because many recording heads are fabricated on each wafer, cleaving the wafer results in the unnecessary destruction of many recording heads. Also, many labor intensive and time consuming steps are involved in cleaving the wafer at the correct place, placing the cleaved wafer in a vacuum chamber, and evacuating the chamber so that the recording head cross section can be viewed in an electron microscope or other viewing device.
Industry needs a simple, rapid, efficient method for performing measurements on microscopic structures and other imaged structures.